The present invention relates to a driving circuit and method for a inkjet printhead, and particularly a driving circuit and method which can effectively reduce the related components and lines by sharing the address lines.
FIG. 1 illustrates a diagram of a printhead and driving circuit for a conventional inkjet device. In the conventional design of the printhead 10 for the inkjet device, the printhead 10 includes many ink chambers Rij. Each ink chambers Rij includes a control switch Cij and an actuators Hij. A driving circuit 20 controls whether these ink chambers Rij eject ink or not. The driving circuit 20 of the printhead 10 includes a driving controller 22 and a plurality of address lines Ai (i=1xcx9cn) and a plurality of paper lines, Pj (j=1xcx9cm), or so called data lines, arranged in a matrix. In this configuration, the address lines are arranged in columns and the paper lines arranged in rows. Each address line Ai and paper line Pj are connected to the corresponding control switch Cij and the actuator Hij.
The driving controller 22 generates driving signals to the plurality of address lines Ai and paper lines Pj. The actuator Hij is driven in such a way when the corresponding control switch Cij is conducted by the simultaneous inputted driving signals from the corresponding address line Ai and paper line Pj. If the control switch Cij is conducted, the corresponding actuator Hij will generate an outward force to allow ejection of the ink from the ink chamber Rij.
FIG. 2 illustrates a timing diagram of the driving circuit for the conventional inkjet device. The driving method for the driving circuit described above is explained as follows. The address lines are inputted with driving signals in sequence, such as in the order from A1 to An or An to A1, to drive the following circuit elements. For example, during time period T1 to T2, only the address line A1 shows a high level signal 24, that means during that time period, only the address line A1 is inputted with the driving signal. Therefore, the address line A1 is active during T1 to T2. Similarly, during time period T2 to T3, only the address line A2 shows a high level signal 26, therefore that means during that time period, only the address line A2 is inputted with the driving signal. Therefore, the address line A2 is active during T2 to T3. In another words, the characteristic of the timing diagram is in that only one of the plurality of the address lines is active at the same time period, however, there would be possibility that all of the paper lines P1xcx9cPm are driven and keep in an active state at the same time period when one address line is driven.
Thus, it is assumed that the control switch Cij is controlled and driven by the address line Ai and the paper line Pj. Only when the driving signals from the address line Ai and the paper line Pj are transmitted to the corresponding control switch Cij at the same time period, then the control switch Cij would be driven and conducted. Consequently, the conducted control switch Cij would then allow the electric current to flow through the corresponding actuator Hij so as to eject the ink in the ink chamber Rij. If only one, or none of the driving signal from the address line Ai and the paper line Pj is transmitted to the corresponding control switch Cij, the control switch Cij would not be conducted and the ink in the ink chamber would not be ejected. When all the address lines are driven for a complete cycle (from T1 to Tn time period), it means that all the actuators for controlling the corresponding ink chambers have been driven once, and the next cycle will start at the time Tn+1. In the above descriptions for the conventional driving circuit 20, it can be referred that (n+m) lines can control (nxc3x97m) actuators at most.
The number of the address line n and the number of the paper line m can determine the maximum controllable number NH of the ink chambers in the printhead. The following condition must be satisfied: NHxe2x89xa6nxc3x97m. That means one address line accompanying one paper line can control only one control switch of one actuator. However, during the same time period, only one address line is inputted with the driving signal and thus in an active state. The other address lines are in the idle state. It means the efficiency of the address lines is too low due to the aforementioned limitation. Furthermore, the conventional driving circuit would become too complex because of the limitation.
Therefore, there is a need to design a new driving circuit to overcome the above limitation and disadvantages. The new driving circuit has to improve the efficiency of the address lines and at the same time, substantially remains the conventional production process of the driving circuit without a distinctive change therein.
The object of the present invention is to provide a driving circuit for an inkjet printhead to improve the efficiency of the address lines. The present invention reduces the n conventional address lines to nxe2x80x2 group-driving lines and nxe2x80x3 column-driving lines, wherein n=nxe2x80x2xc3x97nxe2x80x3, n greater than nxe2x80x2+nxe2x80x3. of the conventional driving method in the prior art that drives an address line at one period of time would be changed to the driving method in the present invention that drives at least a group-driving line and one of the column-driving lines. All the control switches would be divided into different driving groups to be driven by the different group-driving lines. In this configuration, the column-driving lines can be substantially reduced and repeatedly utilized in different driving groups. The number of the conventional address lines can be reduced and consequently, the efficiency is improved. That means, while remaining the control of the same number of the ink chambers, the number of control lines between the printhead and driving circuit can be substantially reduced. This also leads to the decrease of the complexity of external driving circuit for an inkjet printhead.
Another object of the present invention is to provide a driving circuit for an inkjet printhead, which substantially remains the same fabrication procedures. The fabrication procedures of the group-driving lines and the column-driving lines of the present invention is similar to, with only a little difference with, the fabrication procedures of the conventional address lines. Therefore, the cost is not dramatically raised due to the application of the present invention.
The present invention is a driving circuit for an inkjet printhead. The driving circuit comprises a group of group-driving lines, a group of column-driving lines, and a group of row-driving lines. The printhead comprises a plurality of driving groups being driven by the driving signals from the group of group-driving lines. Each driving group comprises a plurality of actuators and control switches being driven by the driving signals from the corresponding column-driving lines and row-driving lines. A control switch is driven and conducted only when the driving signals from a corresponding group-driving line, a corresponding column-driving line and a corresponding row-driving line arrive at the same time period. And a corresponding actuator is accordingly driven to actuate the corresponding ink chamber. The characteristic of the present invention is in that all the control switches in different driving groups are driven by the same group of column-driving lines and the same group of row-driving lines, as long as distinguished by the accompanying different group-driving lines.
When a driving group is driven by a corresponding group-driving line, only those control switches, which at the same time are driven by the corresponding column-driving lines and row-driving lines, of the aforementioned driving group are conducted. The other control switches not of the aforementioned driving group are not conducted.
The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings.